I'm no expert... but you do mention that you think it's down to your knee cap being pulled to one side.
Just in case you're unaware, that is a classic symption of a tight IT Band (Iliotibial Band Syndrome... ITBS).
Try googling that, and using the search function on this forum. That could help you self-diagnose and read advice on how to get over it. But a trip to the physio is not a bad idea! Good luck with it.